Rich connectedness: $10^4$ to $10^5$ synapses per neuron

The brain is praised on its ability to integrate many signals. This is not just an opinion because the average has between 10.000 to 100.000 synapses (human brain)^3.17. The architecture of brain very different from serial processors. Other routes have been suggested and are pursued: Parallel computing, neuromorphic engineering, optic-holographic [PWB87]^3.18 [Nol01, pp. 55, 189-195] and molecular [CdZR93]. Molecular computers may solve the scaling problem.

Apart from a medium for 3D pictures, holography may be a promising method of optical interconnection.

``In contrast with implementations, in which the specifications of the connection patterns must be stored separately from the connections themselves, holographic media can simultaneously provide both the massive physical interconnectivity and the large memory required to specify the connections. This duality is particularly useful in adaptive networks.'' [Ram98]